Biotechnology to help speed up cassava breed

Breeding new plant varieties via conventional methods usually takes more than a decade, but with the assistance of biotechnology, the Thai Tapioca Development Institute (TTDI) hopes using a DNA fingerprint will shorten the time for cassava strain development and result in new varieties for specific uses.

A DNA fingerprint will be applied to match different cassava varieties with desired characteristics before selected varieties are crossbred in the field to see the actual result of the new variety.

Conventional methods entail repetitive crossbreeding of one variety with many others until a satisfactory trait results. The new process can be tested on a computer first to rule out crossbreeds that will bring about unsatisfactory outcomes, leaving only the breeding of carefully selected varieties.

The TTDI is now developing a waxy starch in cooperation with the International Center for Tropical Agriculture, whose scientists have succeeded in deriving a mutant strain with the waxy or amylose-free trait.

This waxy mutant will be crossbred with commercial local varieties to develop waxy tapioca.

Adul Vinaiphat, the institute's vice-president, said waxy tapioca will have much higher value than the regular kind, as waxy starch is in demand by several industries and cannot be substituted by modified starch derived from normal tapioca.

The TTDI expects waxy tapioca to be ready for commercial planting within the next three years. Meanwhile, it must figure out how to protect the expected new plant variety through patent registration to ensure maximum benefit for cassava planters.

"If planters have to pay a high price for their cassava trunks, they'll be in trouble, so we must figure out how to handle this without causing them problems. At the same time, we'll have to find ways to control the smuggling of new varieties to neighbouring countries," said Suthiporn Chirapanda, an adviser to the TTDI.

Searching for high-value varieties is a sustainable solution for the development of the local tapioca industry, which involves some 400,000 households, he said.

Due to an infestation of pink cassava mealybugs for almost two years now, production of fresh cassava roots is estimated at only 21 million tonnes, while demand stands at 30 million tonnes. That means cassava will most likely stay above three baht a kilogramme this year.

Mr Adul said price problems will not plague planters this year, but industry may be worried about quality, as some planters may dig up their cassava roots too early - at about six months instead of the usual nine months.

Roots that are too young contain a low percentage of starch.

This practice may also cause quality issues for the next crop, as planters may not have strong cassava trunks for crop expansion.

Therefore, the institute recommends that planters keep some of their roots in the ground until measurement for use in breeding the next crop.

Yet another potential problem is adulterated tapioca chips from small factories popping up to compete in buying cassava roots from planters, said Mr Adul.

The substandard chips will result in low-quality starch and higher costs for flour factories.